JPS6056436A - Die forging method - Google Patents

Abstract

PURPOSE:To make die forging in one process and to make die mold release very easy, by keeping means a while after forming a through-hole by a punch for hole working, fitting a forging product to the punch by thermal contraction keeping this condition, and releasing the die mold. CONSTITUTION:A material 5 is set in a lower die formed of a lower die 2 and a knockout 4, and the material 5 is pushed out in the die by lowering an upper die 1 and a punch 3 for hole working at the same speed. The punch 3 is lowered by lowering the knockout 4 and the bottom part 6 of hole working part is dropped to obtain a forging product A. The forging product A is held until it is cooled to some degree and dimensional contraction is waited for. When the upper die 1 and punch 3 are raised at the same speed, the forging product A is released from the lower die 2 in the state fitted to the punch 3, and at the same time, raises the knockout 4 and releases remaining materials that become the bottom part 6. When the punch 3 is raised with the upper die 1 fixed, the forging product 1 is released from the punch 3, and the work is completed entirely.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a die forging method for parts having through holes, which enables die forging in one step and facilitates mold release.

Forging has been widely used as one of the methods for forming machine parts, and is used to form many parts.

However, in Figure 1 (al, , (b), C(-)
When attempting to forge a part A7 in which a through hole a and a gear part are formed in the through hole a as shown in FIG. , a pair of upper and lower dies 01 and lower dies 02, and a knockout 03 provided through the lower dies 02.
Only the outer diameter portion is forged, and the next forged product B is released from the mold by a knocker (03) and taken out. Thereafter, the through hole a was punched and machined using a hole punch 04 as a separate process, as shown in FIG.

Also, when forming a gear part in the through hole a, forging was performed as a separate process using a hole processing punch 05 equipped with a gear processing part, as shown in FIG.

The reason why the through hole a is processed in two steps is as follows.
When the outer diameter part is forged simultaneously in the same die with the punches 04 and 05 for punching the through-hole af hole, the -next forged product is formed by the lower die 02.
Even if the knockout 03 is pushed up in an attempt to release the forged product from the lower die 02 after it has been processed with the hole punches 04 and 05, there is no part that touches the forged product and the mold cannot be released. It is.

Therefore, there are disadvantages in that the number of processing steps increases and equipment costs and product costs also increase.

It is an object of the present invention to provide a die forging method which eliminates such conventional drawbacks and allows for forging even parts having through holes in one step, and also allows easy release from the mold. The configuration of the present invention that achieves this object is such that when die-forging a part having a through hole, the hole is machined by passing a hole punch at the same time as the external shape is forged, and this machined state is held for a predetermined period of time. After fitting the forged product into the hole punch through heat shrinkage,
The method is characterized in that the forged product is released from the mold and the hole punch by returning the hole punch to the pre-processing position.

Hereinafter, a case in which an embodiment of the present invention is applied to closed forging will be explained in detail. Fig. 6 is a process diagram of an embodiment of the die forging method of the present invention, and Fig. 7 is a sequence diagram thereof. The upper part of each line diagram indicates upward movement, and the lower part indicates downward movement.

The die forging of the present invention includes a pair of upper and lower dies 1 and 2, a punch 3 for machining through holes and gears provided through the upper die 1, and a knockout 4 for mold release. is used.

First, as shown in FIG. 6(a), the material 5 is set in a lower mold formed by the lower die 2 and the knockout 4,
Above this material 5, an upper die is constructed by an upper die 1 and a punch 3 for punching holes.

After this, in order to start forging, as shown in FIG. 2(b), the upper die 1 and the punch 3 for punching the hole forming the upper mold are lowered at the same speed so that the upper die 1 hits the lower die 2. The material 5 is extruded into the mold so that they are in contact with each other. Next, the same figure (C
), the hole-machining punch 3 is further lowered to fill the mold with the material 5, and gear machining is performed on the outer diameter portion. During this gear machining, by lowering the hole punch 3, the filler plate 5, which was not completely filled in the previous step, is completely filled with the material 5 for forming the hole. In addition, a hole with a bottom part 6 of the previous stage of the through hole a is formed, but this bottom part 6 has an adjustment margin due to variations in the volume of the closed forging material 50, and the upper die 1 due to overfilling. Lower die 2, hole punch 3. Prevents damage to knockout 4 etc. and damage to forging machines. Note that, as a measure of filling, for example, molding load may be used.

After the mold is completely filled with the moon 5 in this way, the same figure (
As shown in d), the knockout 4 is lowered, the hole punch 3 is lowered, and the bottom part 6t of the hole forming part is dropped to perform the forging process and obtain a forged product.

After this, the mold is released, but first, the forged product A is held in the state where the forging process is completed until it has cooled down to some extent, and the size of the forged product A is allowed to shrink due to cooling.

Due to this dimensional shrinkage, the outer diameter of the forged product A tends to become smaller, making it easier to release from the mold, while the through hole a of the forged product A tends to stick to the punch 3 for punching holes, which also has a smaller inner diameter. The two will be in a mated state.

In this case, the cooling holding time is usually about 1 to 2 seconds, and in this time the outer diameter part contracts and a gap is formed between it and the lower die 2, and the inner diameter part shrinks and the hole is closed. The processing punch 3 is fitted into the state. This is because during forging, regardless of whether it is cold or hot, processing heat is always generated, causing expansion of the forged product, and the time required for cooling this is extremely short. In other words, it shrinks due to a slight drop in temperature.

Next, as shown in the same figure (e), when the upper die 1 and the hole punch 3 are raised at the same speed, the forged product A is released from the lower die 2 while being fitted in the hole punch 3. Release from the mold. At the same time, raise the knockout 4 and lower the bottom part 6.
Release the leftover meat from the mold. After that, as shown in FIG. 3(f), when the hole punch 3 is raised with the upper die 1 fixed, the upper die 1 acts as a stopper and the forged product is removed from the hole punch 3. All demolding work is completed.

By performing die forging in this manner, it has been difficult to die forge a component having a through hole in one step, but it can be die forged in one step and can be easily released from the mold.

Furthermore, if closed forging is used, subsequent machining is not required, resulting in more efficient molding and cost reduction.

In the above embodiment, the forged product A having a gear portion on the outer diameter portion is formed. However, if this gear portion has a twist, for example, a helical gear is formed, it may be necessary to , the mold is released by mechanically applying a corresponding twist to the punch for punching the hole, or, if it is possible to release the mold as is, the mold is released without applying twisting rotation. Further, the present invention can be applied to a device that does not have a gear portion on the outer diameter portion, and can also be applied whether or not there is a gear portion on the inner diameter portion.

As specifically explained above with reference to the embodiments, according to the present invention, even in a part having a through hole, the through hole is formed with a punch for punching the hole, and the state is maintained to prevent heat shrinkage. Since the forged product is fitted into the punch for drilling holes and then released from the mold, die forging can be performed in one step and release from the mold is also extremely easy.

[Brief explanation of the drawing]

Fig. 1(a), Φ), ((:) are respectively perspective views of parts having through holes to which the present invention is applied, and Fig. 2~
FIG. 5 is a process diagram of a conventional die forging method, and FIGS. 6 and 7 are a process diagram and a sequence diagram of an embodiment of the die forging method of the present invention. In the drawings, a is a through hole, A is a forged product, 1 is an upper gouge, 2 is a lower die, 3 is a hole punch, 4 is a knockout, and 5 is a raw material. Figure 1 (a) (b) ' Figure 3 10 Figure 4 Figure 5 (c), d (e) (f) Figure 7 - Ginma

Claims (1)

[Claims] When die-forging a part with a through hole, at the same time as forging the external shape, a hole punch is passed through the hole to drill the hole, and this machining state is held for a predetermined period of time to cause heat shrinkage. A die forging method characterized in that after the forged product is fitted, the hole punch is returned to the pre-processing position and the forged product is released from the mold and the hole punch.